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Pilot studies in Canada have
been conducted at the Town of Olds (Alberta) Wastewater Treatment Plant, the
City of Enderby (British Columbia) Wastewater Treatment Plant and the Town
of Ladysmith (British Columbia) Pollution Control Plant to measure the suitability
of the process for primary solids removal.
Results of these
studies indicate that this technology is equivalent or superior
to conventional primary sedimentation for both BOD and TSS reduction (averaging 35 and 55%, respectively). In
addition to the reduction in TSS and BOD, the process also creates
a solids underflow
which has a significantly higher solids’ concentration than that obtained
with conventional primary sedimentation (50% vs. 5%).
ENDERBY,
BC
Waste Water Treatment Plant
The City of Enderby has installed a Salsnes Filter (SF 4000) at their WWTP. This system has been in continuous operation since January 2004 and has been exceeding expectations since that time. The use of the Salsnes Filter has allowed the city to reduce the amount of waste activated sludge produced from their facility from roughly 8-12 m3/day to 1-2 m3/day. This has resulted in significant savings to the city as a result of reduced trucking and disposal costs. Tests are also being conducted to use the Salsnes Filter to dewater the small amount of sludge that is still being produced. Initial results are extremely promising, especially since no polymer or chemical have been required.
In addition to reduced sludge handling, the City of Enderby has benefited from an increase in capacity at their plant. The reduction in solids entering the secondary treatment allows for a much higher flow rate through the existing secondary system.
Dr. Bjorn Rusten (Aquateam consultants, Norway) visited the Enderby facility and determined that an increased treatment capacity of 69% could be expected based on the following calculations:
“The increase in capacity is based on the difference in production of biological sludge with and without a Salsnes filter as primary treatment. With Salsnes primary treatment the biological sludge production will be lower, which means that the load to the treatment plant can be increased while maintaining the MLSS concentration and the SRT at today's values. My calculations were based on a design temperature of 13.5 deg. C, 7.5 days aerobic SRT and that the SVI will be the same with a Salsnes filter as it is today. For a relative comparison of sludge productions I have used the equation for biological sludge production given in the German design guidelines for activated sludge plants (ATV A-131). The ratio of TSS/BOD5 in the influent to the biological stage has a major impact on the specific sludge production (kg TSS produced/kg BOD5 removed). Primary treatment by Salsnes filter lowers this ratio significantly, and also slightly reduces the BOD load. My calculations based on the above, assuming 5 mg BOD5/L in the final effluent, shows the expected biological sludge production after installation of a Salsnes filter to be 59% of the biological sludge production without the Salsnes filter, which indicates a 69% increase in biological stage capacity (1/0.59=1.69). …this is based on 25% BOD5 removal and 50% TSS removal over the Salsnes filter.”
Dr Bjorn Rusten – May 6, 2002
It should be noted that the installed Salsnes Filter has been achieving
40% BOD5 reduction and 68% TSS reduction, significantly more than
what was expected.
Contact Person:
Mr. Alf Soros, Public Works Superintendent
City of Enderby, British Columbia
Ph: (250) 838-7230
LILLOOET,
BC
Waste Water Treatment Plant
A
Salsnes Filter (SF 2000) was installed and commissioned at the Lillooet BC
WWTP in July 2004. This is part of a major upgrade
to the entire
wastewater facility. The Salsnes Filter system has been utilized
to provide sewage treatment while the old “Spirogester” system
is dismantled and a new secondary treatment system is installed.
It is also being used to dewater the sludge that has built up
inside the
Spirogester. The small footprint of a Salsnes Filter has allowed
this upgrade project to be carried out on the same site as the
original WWTP
while maintaining a reasonable level of sewage treatment.
The plan for the new facility also includes a second SF 2000 unit.
This unit will be used to handle peak wet weather flows, assist
with dewatering
WAS and provide redundancy for the first unit.
CAPITAL REGION DISTRICT, VICTORIA, BC
Testing is currently being performed with an SF 2000 in Victoria BC. Testing commenced in May 2004 and is expected to continue through to mid-October. At that time the suitability of the Salsnes Filter for the CRD’s sewage treatment will be determined. These tests are being carried out at the MacAuley Point facility in Esquilmalt, BC.
OLDS,
ALBERTA
Waste Water Treatment Plant
On behalf of the Town of Olds, Aqua-Pure hired an independent consultant, Mr. Tom Graham, to review the application of Aqua-Pure’s demonstration Salsnes Filter (SF2000) in December 2001.
The Salsnes performed beyond expectations with the following results:
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1 |
Reduction in Settleable Solids | 99.7% removal |
| 2 | Reduction in Total Suspended Solids | 55.6% removal |
| 3 | Reduction in BOD5 | 23.6% removal |
| 4 | Percent Solids in De-watered Sludge | 32.3% solids |
It was determined that a
Salsnes model SF6000 filter with a 250 micron belt could easily be
installed into the existing facility with minimal infrastructure modifications.
Contact Person: Mr. Lawrence Allen, Public Works Superintendent
Town of Olds, Alberta
Ph: (403) 556-6981
LADYSMITH,
B.C.
Pollution Control Plant
The
Town of Ladysmith, BC has used a Salsnes Filter (SF2000) for a pilot project
conducted
by Aqua-Pure (2000, 2001).
The project tested
Aqua-Pure’s
electro-coagulation technology (ElectroflocPLUS) for secondary
sewage treatment with the Salsnes Filter as primary treatment.
Earth-Tech Canada (Burnaby, BC) was hired to evaluate the technology.
Below are excerpts from Earth-Tech’s report regarding the performance
of the Salsnes Filter used for primary sewage treatment at Ladysmith:
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(A) |
Salsnes Filter Performance |
| “…By examining the results it was determined that the suspended solids removal efficiency of this process averaged approximately 54%. This is equivalent to the performance obtained by conventional primary sedimentation. The solids content of the filter’s underflow was approximately 50%, which is well below the 4 to 12% common for primary sedimentation, or the 10 to 15% for other screening devices [1].” | |
| (B) | Solids Stream Analytical Data |
| “…the Salsnes Filter was seen as being very effective in concentrating metals, pathogenic organisms, and solids. As an example, the solids stream from the filter had an average value of 50% solids content, and of that, approximately 90% (median value) of the total solids were volatile.” | |
[1] Wastewater Engineering: Treatment, Disposal and Reuse, Metcalf and Eddy, Inc., 3rd Edition, 1991. |
The Town of Ladysmith is in the process of designing their WWTP plant upgrade. The Salsnes Filter has been selected for use as primary treatment.
Contact: Mr.
Gord Horth, Town Administrator
Town of Ladysmith, British Columbia
Ph: (250) 245-6440
PLEASE NOTE:
Additional references from various industries are available upon request.
Tours of Salsnes
installations can be arranged upon request. Call us to make arrangements.
